A known area of application is commercial studio technology, where apparatus with the formats mentioned above are provided as video recorders for the helical scan magnetic tape recording of digital television signals in particular HDTV and are also used as data recorders. The recordings are used, e.g. in a film editing system, predominantly for saving data, also called backup, wherein relatively large data transfer rates have to be taken into account.
As represented diagramatically using a track configuration on the section of a magnetic tape 1 in FIG. 2, digital data signals, also called useful data below, are recorded in so-called clusters 2 by means of two groups of rotating write head arrangements 3a and 3b arranged on a head drum 4, shown in FIG. 3.
In accordance with the D6 format two write head clusters 3a and 3b ago comprise eight individual write heads R1-R8, plus a single erase head. Similarly two read head clusters 5a and 5b comprising eight individual read heads P1-P8, which can provide read after write or direct off-tape monitoring during recording. Consequently, eight parallel slanted tracks are written by each head group forming a cluster 2, with two clusters corresponding to a full head drum revolution. The number of clusters (2) for a frame depends on the respective video standard: for example, in the case of a 25 video frames per second standard, a total of twelve clusters (2), arranged next to one another are provided for the data of a video frame. In this case, two adjacent clusters (2) in each case form a segment 6 and six adjacent segments in each case form a data frame 7, 8.
For the interaction of drive by means of the servo devices thereof and the feeding and also processing of the useful data, the clusters 2 are assigned indexes which are formed as markings and are recorded as a longitudinal track 10 parallel to control track 11 on the magnetic tape 1.
In the event of a transfer rate of useful data fed to the apparatus which e.g. in the case of variation of the data processing speed within the film editing system is lower than the constant apparatus recording rate, the magnetic tape is utilized incompletely because affected locations are filled with dummy or non-usefull padding data in order to ensure a continuous data recording. The advantageous invention obviates the recording dummy data and therefor utilizes the magnetic tape more efficiently.